1. Field of the Invention
The present invention relates to a display device for displaying predetermined contents on a reflection display.
2. Description of the Related Art
This type of display devices includes a display device for displaying contents such as an electronic book on a reflection display such as a Cholestric liquid crystal or an electrophoretic display for showing the contents to a user as described in JP11-271799A.
Such a display device is adapted to display contents on its reflection display. Thus, as a display device become lighter and thinner, for example, the display device has a risk of an unauthorized copy letting someone place the screen of the reflection display on a contact glass of a copy machine with its face down and copy contents on its screen.
Generally, a conventional display device is so heavy and thick that nobody can place it on a contact glass of a copy machine. The industry does not seriously consider the risk of an unauthorized copy in the abovementioned way. The conventional copy protection method prevents data on contents from being copied and protects the contents against a copy from an electronic medium to another electronic medium. The conventional copy protection method is vulnerable to an unauthorized copying of contents displayed on a screen directly from the screen. The conventional display device is not protected by any technical means against the unauthorized copy, which is done by copying contents on the screen with imaging means such as a copy machine.
The present invention intends to solve the abovementioned technical problem. An object of the present invention is to provide a display device for protecting contents on the display screen against being imaged with an imaging section as they are.